In recent years, with the rapid development of semiconductor technology, portable electronic products and flat panel display products have also emerged. Thin film transistor (TFT) liquid crystal displays have become standard output devices for various data products because of their advantages such as low operating voltage, no radiation scattering, light weight, small size etc. A thin film transistor liquid crystal display is generally composed of a matrix of pixels arranged in both a horizontal direction and a vertical direction. When the thin film transistor liquid crystal display performs display, it needs to generate a gate input signal and sequentially scan various rows of pixels from a first row to a last row. In the thin film transistor liquid crystal display, this is done by an appropriate gate driver. In general, the gate driver is composed of a plurality of stages of shift registers connected in series, wherein an output signal of a previous stage of shift register is used as an input signal of a next stage of shift register.
In order to reduce the production cost of the thin film transistor liquid crystal display, manufacturers in the industry manufacture multiple stages of amorphous silicon shift registers and a gate driving circuit (i.e., a GOA driving circuit) directly on a glass substrate of a panel by using an amorphous silicon process to replace a gate driver in the related art, so as to reduce the production cost of the liquid crystal display.
In the GOA driving circuit, a simple group of frame start signals STV and a clock control signal CLK are input, a gate signal is transmitted stage by stage through a cascaded circuit on the panel, and the STV and CLK signals have the same output levels. However, in practice, due to the difference in resistances of fan-out areas of panels of thin film transistors and the difference in process characteristics of the panels, it is easy to cause a difference in charging voltages of different rows, and thereby a vertical line defect due to insufficient charging occurs on the panel.